Scoring on Used Thiels here

Thiels have always had fairly poor resale value.  It's a testament to the bad taste of an awful lot of audiophiles.  I got a used pair of 2 2s 7 or 8 years ago and they were a revelation.  For a small amount of money I got some fantastic sounding speakers that do nothing wrong.  They were laughably better than anything I'd ever heard around the price.  It took me a while to admit it but when it comes to enjoying listening to music they were better than the B&W N802s I had at the time.  I traded the B&Ws in for Thiel 3.7s and haven't looked back.  

I have been pondering some different speakers in my second system.  

Amp is 60w/ch Bel Canto c5i.   Current speakers in there are 90db efficient Triangle Titus XS and a sub.  

These sound great but am interested in trying something different and bigger.  Waf is a factor.  

Thiel appeals to me.  The low efficiency is a concern for me.   Its a large family room kitchen area.  I do not need to go uber loud in there but do like modest volume levels when I can.   Most of the time things are not played loud in there.   I go down to my main rig for that.  

Klipsch Heresy III has been a leading contender.   I have heard and liked these and the higher efficiency is a plus.  

I've used OHM Dynaudio and the Triangle speakers with the c5i and they all sound wonderful ( but different).  

c5i is very airy and detailed with no edge ever.   I feel like most any speaker could work well with it save for volume limits with only 60w/ch.  

is that enough for any particular model Thiel?      

Enough for many, but perhaps not ideal.

Was an owner of the CS 1.5, 2.2 and 2.3 but the 2.2 were my all time favorite and listening to piano music from another room sounded unbelievably real; newer drivers were not my cup of tea.

Wig

Thiel appeals to me.  The low efficiency is a concern for me.

The efficiency is about average, actually. Most models rated 87-89 dB. The "problem" is the low impedance. Thiels draw a lot of current. You will want a high quality amp with a decent 4 ohm rating.

Years ago I drove a pair of CS1.6s with an Ayre AX-7e. That amp is rated at "only" 60 W but doubles into a 4 ohm load. That amp had plenty of balls to drive the Thiels as loudly as I wanted.

The amp quality part is very important. Thiels are highly resolving and will reveal weaknesses in your amp, cables, and sources. I'd MUCH rather have a high quality 60 W amp (again, with a 4 ohm rating) than a 200 W meh amp. BTW, a zero-feedback design sounds fantastic with Thiels, IME.

What Thiel models are you considering?